Comment # 7 on bug 954482 from Stanislav Brabec

The fix is on its way to Leap 42.1, as part of a large update batch:

Thu Nov 26 14:22:57 CET 2015 - mkoutny@suse.com

- fstrim: Remove Persistent= directive (anacron like behavior) for
  systemd < 212
  (SLE12: bsc#956540, SLE12 SP1: bsc#953691, Leap 42.1: boo#954482,
  util-linux-fstrim-not-persistent-timer.patch).